1. Field of the Invention
The present invention relates to a phosphor layer-covered optical semiconductor element, a producing method thereof, an optical semiconductor device, and a producing method thereof, to be specific, to a method for producing a phosphor layer-covered optical semiconductor element preferably used for an optical use, a phosphor layer-covered optical semiconductor element obtained by the method, a method for producing an optical semiconductor device using the phosphor layer-covered optical semiconductor element, and an optical semiconductor device obtained by the method.
2. Description of Related Art
An optical semiconductor element is obtained by being cut from one wafer into a plurality of pieces. The optical semiconductor element is mounted on a board to be further covered with a phosphor layer, so that an optical semiconductor device is produced.
As a method for obtaining an optical semiconductor device using an optical semiconductor element, for example, the following method has been proposed (ref: for example, Japanese Unexamined Patent Publication No. 2007-123915).
That is, a dominant wavelength (a wavelength obtained by adding a visibility curve to an emission spectrum) of radiated lights of a plurality of LEDs cut from a wafer is measured. Then, a plurality of the LEDs are classified into groups in accordance with the range of the dominant wavelength, to be specific, a group consisting of 440 and 445 nm, a group consisting of 445 and 450 nm, a group consisting of 450 and 455 nm, and a group consisting of 455 and 460 nm and each of the LEDs of the groups is mounted on the respective boards. Separately, a plurality of phosphor sheets each containing a phosphor with a concentration that corresponds to the dominant wavelength are prepared. Next, each of the phosphor sheets with a phosphor concentration that corresponds to the dominant wavelength of the group is deposited on the board and the LED to be then cured by heating.
In Japanese Unexamined Patent Publication No. 2007-123915, the phosphor sheet with a phosphor concentration that corresponds to the dominant wavelength of the LED is deposited on the corresponding LED, so that a desired color tone (a desired degree of whiteness) is obtained.